Apparatus for making concrete pavements



R'. W. BAILY APPARATUS FOR MAKING CONCRETE PAVEMENTS Sept. 9, 1941.-

F'iled Feb. 7, 1951 INVENTOR APPARATUS "FOR. MAKING CONCRETE PAVEMENTSRobert W. Baily, Philadelphia, Pa.

Application February 7, 1931, Serial No. 514,124

6 Claims.

My invention relates to improvements in apparatus for making concretepavement.

It is one object of this invention to provide a novel apparatus forstriking off the surface of concrete or other material during the makingof a roadway or similar structure. I provide a screed member in front ofwhich the unformed mass of concrete is deposited and by which this massis leveled and rapidly and intensively vibrated to cause the concrete tobecome more dense and fluent and also to cause the elimination of air.and water entrapped in the concrete. It is the particular object of thisinvention to concentrate all or the greater part of the describedvibration to the unformed-concrete in front of the screed member.' ThisI preferably accomplish by attaching the vibrating mechanism to the backof the screed member. Another object is to maintain the screed member ata predetermined level above the sub-grade line so that the surface ofthe concrete will have a uniform finish. It is also an object of thisinvention to provide a screen by which the described vibration may betransmitted vertically to the concrete after it has been struck off,some of the vibration being transmitted -horizontally to the unformedconcrete through a screed member having a vertical face which may betilted to a slight degree either forwardly or backwardly. Other objectsappear hereinafter.

Referring to the accompanying drawing, Fig. 1 is a perspective viewpartly in section and partly broken away showing my invention inconnection with both unformed concrete inj'froi t of the screed memberand a completed slab below the same. Fig. 2 is a detail section of thescreed member on the line 22 on 1- carrying the vibrating mechanism inconnection with an attachment at the upper side for leveling theunformed concrete. Fig. 3 is'a plan view of Fig. 2 with parts i, 3, l8and I9 omitted. Fig. 4 is a view on a reduced "scale of Fig. 2 rotatedto the right 90. Fig. 5 is a detail like Fig. 2' with the top screedmember omitted and the righthand screed member tilted slightly to theright. Fig. 6 is a view like Fig. 5 but having the screed member tiltedto the left of the position shown in Fig. 2.

Referring to the drawing, I designates a screed member extending fromone side of the roadway to the other and having its ends resting uponthe side forms 2 .which form mold members for the sides of the concreteroadway. The screed memher is preferably made of steel and is shown tobe a channel member having its ends closed by plates 3 through whichbolts 4 are passed. for securing the ends of the screed member to the"members 5 having horizontal portions 6 riding on top of the forms 2. Thescreed member is shown' with its front or right hand face vertical, butit may be inclined forwardly or rearwardly of its vertical position byremoving the bolts 4 and passing them through other pairs of holes 4' inthe members 5. The .members 5 are provided with handles 1 by which thescreed can be moved along the roadway and on the side forms 2, but

these handles merely indicate the presence of some means for moving thescreed rather than the indication of any particular means for moving it.

The rear face of the screed member I carries two pairs of housings 0extending rearwardly at right angles theerfrom. A horizontal shaft 9 ismounted in these housings and is driven by the band wheel I 0 secured tothe shaft. This band wheel may be driven by any suitable prime moversupported and having travel in any suitable manner, as on the side forms2. Each pair of hous- .ings has a crank l0 secured to the shaft, eachlying in front of the screed sothat it may be levedge of the screedmember I.

eled and formed into a slab such as l5 which has already been made bythe forward movement of the screed which struck off the concrete so asto produce the upper even surface N5 of the slab.

As the screed member advances, the shaft 9 is driven rapidly, preferably2,500 revolutions or more per minute though good results may be obtalnedat 2,000 revolutions per minute. This very rapid vibration of the screedis transmitted to the unformed mass of'concrete H which is convertedfrom a rather stifl. mass to a practically fluent and dense mass, freedof substantially all of its air and excess water. Some vibration will betransmitted from the up and down movements of the crank to the slab l5through the platform member l9 extending rearwardly from the lowermember l9 has its ends welded or otherwise secured to the\end members 5of the screed. Such vertical vibration tends to eliminate any air orwater which may remain in the slab. I find that vided with wings H whichextend out over the The platform I side forms 2 to scrape any concretefrom the side forms upon the mass of concrete I4.

As shown in Figs. 2 and 4 the screed member I may have bolted orotherwise secured thereto the auxiliary screed member I8 at right anglesto the screed member I and at the upper edge thereof, the screed memberI8 extending out over the housings 8 at the rear of the screed member Iwhen the latter is vertical. The platform member I9 cooperates with thescreed member I in striking off the concrete of the road slab and alsofunctions to impart surface vibration to the concrete below it. Themembers I9 and I may be bolted to the end members so that the platform I9 forming one ,of the screed members is horizontal and the member I isvertical. The forward edge of the platform I9 and the lower edge of themember I afford a transitional cylindrical surface as shown in Figure 2.The member I may be adjusted by changing the bolts 4 to different holesfor prying to cause the screed member I to incline rearwardly as, forinstance, as illustrated in Figure 2, or to cause it toincline forwardfrom lower edge as shown in Figure 5 where both members I9 and I arebolted to the end members 5. They may be adjusted byproper arrangementof the fastening bolts until the member I is in horizontal position asillustrated in Figure 4 and the member I8 is in vertical position sothat the member I becomes the leveling screed cooperating with themember I8 for striking off the concrete. When the parts are in theposition shown in Figure 2 the more powerful vibrations are directedforwardly. When they are in the position shown in Figure 4 the morealways maintains its platform in contact with the upper surface of theslab, this being an improvement over vibrators which project themselvesalong .the roadway by small leaps or jumps. This application embodies amodified form of the features shown in my application Serial Number428,747, filed February 15, 1930 and restricted to methods which theapparatus of the including a front member adjustable to various powerfulvibrations are directeddownwardly so far as the effect on the concreteis concerned.

Fig. 5 shows the screed member I tilted forwardly. It is tilted this waypreferably when the unformed concrete mass I4 is rather harsh or stiff.The screed member I is shown in Fig. 6 tilted rearwardly. It ispreferably given this position when the concrete mass I4 is rather softor plastic.

This invention avoids the necessity of using perforated or slottedplatforms orthe like on the finished grade line for the purpose ofletting entrapped air and excess water escape. There is very little orno air and excess water in the slab as the screed member passes over theslab because all or practically all of the entrapped air and excesswater is vibrated out while the concrete is in engagement with theforward face of the screed member I. It is to be noted that theapparatus described is in no sense a tamping apparatus. It is also to benoted that the screed angles relative to a pavement slab, and vibratormechanism carried by said front member.

2. In apparatus of the kind described, a vibrating apparatus having amain and an auxiliary elongated parallel contacting. screed membersforming a front face and trowel member respectively, arranged to liecrosswise of a roadway slab being constructed, for movement along theroadway, means mounted on the front face member for vibrating theapparatus to impart to unformed concrete deposited in front thereof,

rapid and intense vibrations, and for imparting the major intensity ofthe vibrations to the concrete in front of the apparatus and the minorintensity of the vibrations being imparted to the concrete below themember.

3. A screed having a base plate and an upwardly extending front plate,a. transverse drive shaft 'mounted on one face of said front plate, of!-center weights connected at spaced intervals to said drive shaft, andmeans for rotating the drive shaft whereby vibrations are imparted tothe screed.

4. A screed having a base plate and an upwardly extending front plate,and vibrators mounted on one face of the front plate.

5. A screed having a base plate and an upwardly extending front plate,and vibrators mounted on one face of the front plate, and an adjustableconnection between the front plate and the base plate whereby the anglebetween the two may be selectively adjusted.

6. A screed having a. base plate equipped with end plates,'a front plateextending upwardly from the base plate and adjustably connected to theend plates, and vibrators mounted on one face of the front plate.

ROBERT W. BAILY.

